The Guide to Shoulder Pain

Have you ever been told you have "tight" upper traps causing shoulder pain? Perhaps someone has said your shoulder blade moves abnormally causing "impingement"? Maybe you've been told to avoid certain movements, like upright rows, because it's bad for your shoulder health. If you've heard these narratives or other explanations for shoulder pain then this guide is for you. In this guide we will seek to bring clarity to shoulder pain while providing research based information regarding the legitimacy, or lack thereof, for common narratives used to explain shoulder pain. Finally, we will lay out a practical path forward for dealing with the issue. Let's get started.

Basic Anatomy Lesson

The shoulder consists of two primary joints:

1. Glenohumeral (GH) joint

2. Acromioclavicular (AC) joint

The GH joint is considered a "ball and socket" joint where the head of the humerus articulates with the glenoid cavity of the scapula. The GH joint has significant freedom for movement. The AC joint is created by the clavicle (i.e. collar bone) articulating with the acromion process of the scapula (see Figure 1). From a sport related injury perspective, we often hear of folks dislocating the GH joint while separating the AC joint.

Although this region of the body involves many muscles, we will focus on four:

1. Supraspinatus

2. Infraspinatus

3. Teres minor

4. Subscapularis

Collectively, the above muscles are known as the rotator cuff, a common area receiving surgical intervention.

Shoulder Pain

Although many claim to know the exact answer to "Why does my shoulder hurt?", rarely do we as healthcare professionals have a specific tissue issue to put our finger on that needs direct intervention. Rather, shoulder pain is a multifactorial experience and there are only a few key scenarios in which immediate healthcare consultation is needed to ensure long-term positive outcomes (e.g. function) are achieved. These scenarios include:

• Accompanying chest pain with shoulder/arm pain

• Recent trauma (e.g., fall) resulting in fracture, dislocation, or separation

• Progressive neurological symptoms (e.g., loss of arm or hand movement, worsening numbness/tingling in arm(s) or hand(s))

Although these scenarios can be concerning, they are not as common as general shoulder pain. We can think of general shoulder pain as shoulder pain that may or may not occur with radiating symptoms into the arm and hand where no trauma occurred and no other symptoms are ongoing. Note, having such a label as general shoulder pain is good news and means we do not have to unnecessarily worry ourselves with finding a specific tissue issue to try and fix. Rather, we can look ahead on how to move forward on the path to recovery. Before moving on to answering the question, "Why does my shoulder hurt?", be sure to checkout the blog - What is pain?

Causes of Shoulder Pain

In this section we will discuss common explanations for shoulder pain while exploring supportive, or lack thereof, evidence for the narrative.

There are 4 common narratives used to explain shoulder pain:

1. Scapular Dyskinesis

2. External Impingement

3. Internal Impingement

4. Rotator Cuff Tears

Scapular dyskinesis is a medical phrase for saying the shoulder blade is moving

abnormally. Previous understanding of arm movement stipulated that when the arm is being raised to the side (see Figure 3), the scapula should upwardly rotate, posteriorly tilt, and internally/externally rotate - together these movements are known as scapulohumeral rhythm. Theoretically, this normative movement avoids damage of subacromial tissue (e.g., supraspinatus tendon). Although superficially this sounds plausible, when we dive deeper into the understanding of movement, tissue alteration, and relationship to pain the narrative lacks foundational support. In this context, the operational model for examining movement is known as the kinesiopathological model (KPM), which creates a false dichotomy of good vs bad or normal vs abnormal movement. Since the 1940s, proponents of this model have postulated the idea of a 2:1 scapulohumeral ratio in which every 2 degrees of humeral elevation results in 1 degree of scapular upward ratio. If someone visually appears to deviate from this movement pattern, then their movement is labeled as abhorrent or demonstrating dyskinesis.

However, the research evidence demonstrates the true range of scapulohumeral rhythm is somewhere between 1:1 - 6:1, which implies much more of a spectrum of normal rather than a dichotomy. This evidence demonstrates movement can vary for a host of reasons such as how researchers choose to measure movement, the plane of elevation, external loading, speed of motion, pain, and fatigue. Where things get interesting, most clinicians evaluate scapular movement visually by watching a patient lift their arms overhead, but this method is not without flaws.

Wassinger et al found clinicians were unable to accurately or reliably differentiate between patients with and without shoulder symptoms based on arm movement alone (see table 1). Wassinger 2015

Plummer et al took this a step further by comparing two clinicians' visual assessment of shoulder mechanics in 135 participants with and without shoulder pain. The catch, one examiner was aware some participants had shoulder pain (unblinded) and the other was not (blinded). Two interesting findings emerged. One, the prevalence of scapular dyskinesis was very similar in participants with and without shoulder pain. And two, the unblinded examiner consistently rated the presence of scapular dyskinesis higher than the blinded examiner when assessing those with shoulder pain. Plummer 2017 Recall, from our I want to believe series - part 2, this is called confirmation bias, where we seek out confirmatory evidence to support a prior held belief. In this context, being tasked with assessing shoulder mechanics while knowing a person reports shoulder pain increases the likelihood we find a supposed problem to label to explain pain based on our prior held beliefs about what is likely causing the pain. Just one of the many reasons why our foundational beliefs about pain are important.

Why is scapular dyskinesis concerning to clinicians?

Recall, many believe movement exists in a dichotomy of injurious vs safe. If they feel scapular dyskinesis has been identified, then it can explain shoulder pain while also acting as an important modifiable risk factor to decrease tissue degeneration and future shoulder pain. As discussed above, dyskinesis isn't meaningfully defined and does not correlate with shoulder pain. However, we will see this illogical thinking through to the next step, shoulder impingement. Most clinicians assume scapular dyskinesis will lead to subacromial (i.e. beneath the acromion process) impingement of the rotator cuff. The impingement supposedly leads to fraying of tissue and eventually rotator cuff tears. Outside of the premise of scapular dyskinesis being flawed, the evidence is unsupportive of a meaningful relationship between scapular dyskinesis, subacromial impingement syndrome (SIS), and shoulder pain. Ratcliff et al conducted a systematic review on the topic and found

This systematic review of the research investigating scapular orientation and kinematics in people diagnosed with SIS, when compared to asymptomatic controls, concludes that a synthesis of the current research findings suggests that no definitive relationship exists between scapular orientation and SIS. [emphasis mine] Ratcliff 2014

McQuade et al makes this statement regarding scapular dyskinesis,

...the observed abnormal motion may simply represent normal kinematic variability. McQuade 2016

At this point, many clinicians may be saying they don't just visually assess movement, but they also use their hands to "test" for scapular dyskinesis.

Unfortunately, no physical examination test has been able to accurately identify those with specific shoulder pathology or pain. Wright et al conducted a systematic review on the matter and found:

None of the studies included in this systematic review reported an ability to discriminate between those with and those without shoulder pain or a specific pathology based on findings from scapular physical examination tests. Wright 2013

With this in mind, some rehab clinicians may notice an exercise program specifically focused on scapular position and mechanics may improve patient shoulder pain symptoms, however this is likely due to playing off of therapeutic relationship, natural history, regression to the mean, and exercise induced hypoalgesia (which is a fancy way of saying movement may feel good) rather than anything specific to the scapula or shoulder mechanics. Polaski 2019 Testa 2016 Hartman 2009 The totality of data at this time does not support a specific scapular-focused exercise regiment as a necessary component of rehab for shoulder pain. Reijneveld 2017 Saito 2018 More to the point, even if a scapular focused program is utilized, it doesn't appear to influence scapular position or motion in those reported to present with scapular dyskinesis. Moghadam 2019 Begging the question, why are folks still hung up on this idea? Tradition is a powerful and appealing approach that takes time and substantial evidence to overcome.

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Recap:

To close, scapular movement is variable, contextually dependent, and based on task completion. Although scapular dyskinesis is a popular narrative to explain shoulder pain, our scapular assessments lack validity and meaningful correlation to symptoms. Finally, although we can intervene with exercise at the scapula level, it has little to do with specific exercises altering scapular position or movement and more to do with doing something is better than nothing. In this next section we will work our way through another popular narrative related to scapular dyskinesis, shoulder impingement. This particular narrative leads to one of the most popular orthopedic surgical interventions, subacromial decompression. But is it necessary?

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"Shoulder impingement" is a common discussion amongst coaches and healthcare professionals. As described above, the narrative outlines how soft tissue structures of the shoulder become compressed between bony surfaces of the joint. There are two types of shoulder impingement commonly discussed in the scientific literature: "internal" and "external". We will initially explore external impingement given it is the more prevalent explanation for shoulder pain in general population.

The Origins of “External Impingement”, a.k.a. Subacromial Impingement

The idea of shoulder impingement was introduced in 1972 by orthopedic surgeon Dr. Charles Neer. We will spend a good bit of time discussing Neer’s seminal paper, Anterior Acromioplasty for the Chronic Impingement Syndrome in the Shoulder: A Preliminary Report, because it sets the stage for the next several decades of biomedical intervention. Neer 1972

Dr. Neer examined the scapulae of 100 cadavers and found that 11 “revealed alterations attributable to mechanical impingement”. Neer 1972 He hypothesized how the supraspinatus tendon might become “impinged” under the acromion process (or associated bone spurs) during certain movements, and become damaged or degenerated as a result.

He writes:

At about 80 degrees of abduction, the critical area of the supraspinatus tendon passes beneath the acromioclavicular joint and this joint tilts with overhead elevation of the arm. With the joint in this position, it is logical to assume that excrescences on the undersurface of the anterior margin of the acromion may impinge on the cuff. Arthrograms seem to substantiate this point. Neer 1972

Dr. Neer then proposes that this impingement could be fixed through surgical intervention.

One should therefore remove the anterior edge and the undersurface of the anterior process along with the attached coraco-acromial ligament. If other pathological areas are discovered at operation, that is, a hypertrophic acromioclavicular joint, or spurs and adhesions at the long head of the biceps or greater tuberosity, they too should be removed. The attachments of the deltoid should be minimally disturbed. Neer 1972

In the 1972 article, Dr. Neer claims to have been performing such procedures, known as anterior acromioplasties, since 1965. He presents a summary of 50 operations that were completed on 46 patients between 1965-1970.

The pre-operative physical exam of these patients revealed crepitus (i.e., joint noise such as clicking and popping), tenderness over the supraspinatus tendon, and the painful arc sign (pain between 70 and 120 degrees while abducting the arm), along with pain at the anterior edge of the acromion during forced elevation. Neer 1972 The only common findings on imaging among the participants were cysts or sclerosis of the greater tuberosity. Dr. Neer then states,

… but on close inspection many [X-rays] showed corresponding areas of proliferation at the anterior edge of the acromion. Neer 1972

How many demonstrated this? We don’t know. Whether this is meaningful, we will discuss later. Dr. Neer goes on to rationalize his surgical intervention:

The value of anterior acromioplasty is thought to be that it relieves pain and inflammation from chronic impingement; that technically it improves exposure of other involved structures and allows appropriate measures to be taken with reference to them; and that it retards the wear caused by persistent impingement and may prevent rupture of the supraspinatus tendon or of the long head of the biceps, or both. Neer 1972

Dr. Neer performs his intervention and follows up with patients anywhere from 9 months to 5 years post-operatively. If this sounds odd, that’s because it is odd to have such a broad and inconsistent range of follow-up times for subjects after intervention. This opens up the potential for natural history and regression to the mean to be plausible explanations for observed outcomes, most especially given the lack of a comparative control group (no intervention).

Ketola et al demonstrated these effectiveness issues in their study comparing a surgery + exercise group to an exercise-only group for shoulder impingement syndrome. The authors report:

The results at 2 and 5 years were similar between treatment groups and they seemed to continue to improve in a similar way in both groups after the first 2 years (to the 5-year follow up). The effects of both procedures appeared to be long-lasting and to continue to improve over time. Ketola 2015

The authors go on to ask the question,

Do these good results reflect the therapeutic intervention, or the natural long-term course of this syndrome?” Ketola 2015

During the study the authors allowed participants who were not satisfied with exercise alone to cross over and undergo surgery (18 participants). We might expect these patients to improve after surgery, but they actually did not. The authors go on to state:

We believe that there was a similar group of patients in the combined group as well, who would not respond to surgery either. So it appears that almost one-third of all patients with this diagnosis do not respond to any sort of treatment. The remaining two-thirds will get better irrespective of the nature of the treatment. It might well be that the natural course of the shoulder impingement syndrome contributes substantially to the improvement of those patients who are 'healed' after treatment, during the 5-year follow-up. It appears that patients who do not get better with nonoperative treatment do not get better with operative treatment either, although this may also partly depend on the duration of the symptoms before initiation of the treatment. This in any case challenges the previous guidelines of offering surgery to patients who 'fail' with nonoperative treatment. [emphasis mine] Ketola 2015

The authors go on to advocate for more research with longer follow-up periods to accurately assess the natural history of subacromial impingement syndrome.

Circling back to Dr. Neer’s findings. Post-operative results are shown in table 2 below.

Post-operatively, patients were dichotomized between “satisfactory” and “unsatisfactory” outcomes:

• Satisfactory = patient satisfied with surgical procedure, with no significant pain. Complete use of the shoulder, less than 20 degrees of limitation of overhead extension, and ≥ 75% of normal strength.

• Unsatisfactory = not meeting above standards. Neer 1972

Thirty-eight out of forty-seven (~ 80%) cases were considered satisfactory, which is quite good results. However, as mentioned above, the lack of a control group means major confounders were not assessed, such as placebo-like contextual effects related to therapeutic ritual, natural history, and regression to the mean.

Benedetti, a leading researcher into placebo, discusses this issue further:

A real placebo effect is a psychobiological phenomenon occurring in the patient’s brain after the administration of an inert substance, or of a sham physical treatment such as sham surgery, along with verbal suggestions (or any other cue) of clinical benefit. Therefore, the effect that follows the administration of a placebo cannot be attributable to the inert substance alone, for saline solutions or sugar pills will never acquire therapeutic properties. Instead, the effect is because of the psychosocial context that surrounds the inert substance and the patient. Benedetti 2011

There was no attempt to understand or account for placebo effects in Dr. Neer’s study. Specifically, there was no control group, and no blinding took place despite the fact that randomized controlled trials were standard practice in research by this time. Unfortunately, this tends to be the case for many orthopedic procedures that initially appear to be superficially plausible from a biomedical perspective prior to undergoing more rigorous controlled study.

However, in 2017, forty-five years after Dr. Neer’s original paper, we have such trials. Beard et al published, Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial.

The CSAW (Can Shoulder Arthroscopy Work?) study aimed to compare 3 groups: subacromial decompression versus sham (“placebo” arthroscopy) versus no treatment. A total of 313 patients were recruited and randomly assigned as follows: 106 to decompression surgery (removal of tissue/bone), 103 to sham arthroscopy (“placebo” surgery with no removal of tissue/bone), and 104 to no treatment. All participants were then reassessed 6 and 12 months later using the Oxford Shoulder Score as an outcome measure. Beard 2018

Results showed that outcomes after surgical decompression are no better than sham surgery and both are only slightly better than no treatment at all (although the clinical significance of this difference is questionable). Their conclusions:

In conclusion, we showed that, in patients with persistent subacromial shoulder pain due to impingement, improvement in Oxford Shoulder Scores with arthroscopic subacromial decompression did not differ to that achieved with arthroscopy only (placebo surgery). Although both types of surgery provide greater symptom improvement than no treatment, this difference was of uncertain clinical significance. The findings (which should be communicated to patients during the shared treatment decision-making process) question the value of this type of surgery for these indications, and might discourage some surgeons from offering decompression surgery and dissuade some patients from undergoing the surgery. [emphasis mine] Beard 2018

A similar study was conducted by Paavola et al, Subacromial decompression versus diagnostic arthroscopy for shoulder impingement: randomised, placebo surgery controlled clinical trial. In this study, 59 patients were randomized to subacromial decompression surgery, 61 underwent sham arthroscopy, and 71 underwent exercise therapy. Patients were reassessed for pain severity at 3, 6, 12, and 24 months after intervention. The study results showed both the subacromial decompression and sham arthroscopy groups dramatically improved, and by 24 months no differences were identified between the surgery and sham surgery groups. Paavola 2018

What about subacromial decompression vs. exercise therapy? Both groups demonstrated substantial improvement from baseline to 24 months. There was a statistically significant difference supporting decompression over exercise at the 24 months mark, but the mean difference between the two groups did not meet the pre-specified minimal clinically important difference (MCID). MCID refers to the smallest possible change in outcome that would be important to a real-world patient, or justifies a change in a patient’s management. This means that the difference observed in the study between surgery and exercise groups was not a meaningful difference for real-world patients.

The authors conclude:

The results of this randomised, placebo surgery controlled trial show that arthroscopic subacromial decompression provides no clinically relevant benefit over diagnostic arthroscopy in patients with shoulder impingement syndrome. The findings do not support the current practice of performing subacromial decompression in patients with shoulder impingement syndrome. [emphasis mine] Paavola 2018

Major takeaway, it appears that pretending to relieve subacromial impingement is just as effective at improving symptoms as actually relieving it. This studies should make us question Neer’s original hypothesis attributing the syndrome to mechanical compression.

Where does this leave us? We have an outdated biomedical narrative from the 1960s that continues to be disseminated to patients, remains unsubstantiated, and results in the rationalization of an invasive treatment that offers no meaningful benefit over sham surgery.

What about less invasive treatments, such as corticosteroid injections?

A recent systematic review and meta-analysis by Steuri et al examined the research on conservative treatment options including corticosteroid injections, NSAIDs, exercise, manual therapy, ultrasound, extracorporeal shockwave therapy (ECSWT), and taping. It is worth noting that this review is based on very low quality evidence; with that said, the authors conclude:

Exercise, especially shoulder-specific exercises, should be prescribed for all patients with shoulder impingement. The addition of manual therapy, tape, ECSWT and laser might add a small benefit. For other non-exercise physical therapy modalities, we cannot provide enough evidence for or against, therefore they should only be used in addition with exercise. Corticosteroid injections seems to be a valid alternative only when exercise or other modalities are not possible while NSAIDS can be helpful, if necessary, in addition to exercise. Steuri 2017

In 2019, Cook and Lewis pondered the question further with their article, Rotator-Cuff related Shoulder Pain: to Inject or Not Inject. Ultimately, the authors concluded injections are no more effective than other non-pharmacological interventions such as exercise. They went on to state,

The continued use of injection therapy in the treatment of RCRSP [rotator-cuff related shoulder pain] has been attributed by some to force of habit and an underappreciation of the placebo effect. Furthermore, its cost-effectiveness has also been questioned. Currently, clinicians and those considering undergoing a shoulder injection for RCRSP should remain cautious due to the poor quality of research evidence. Cook 2019

Take-home message: We need to get patients moving to tolerance as soon as possible, preferably with exercise geared specifically to their goals.

The Power of Narrative

An overarching theme at Tame Pain is the importance of the words we use with patients and clients. So, what are the issues associated with delivering this idea of tissue being “impinged” by the acromion or bony outgrowths? Cuff et al published a study in 2017, Subacromial impingement syndrome – What does this mean to and for the patient? A qualitative study. The authors examined patients’ understanding of subacromial impingement syndrome and its effect on treatment selection and rehabilitative care.

The authors argue that the diagnosis of subacromial impingement syndrome (SIS) reflects a biomedical narrative that instills fear and avoidance of movement among patients. Patients are told they have a bony outgrowth that impinges with particular shoulder movements, thus damaging, degrading, or “fraying” underlying tissues over time. Cuff 2018

In response, many naturally become fearful and, potentially unbeknownst to them, begin self-selecting movements they deem “acceptable” vs. “unacceptable” for fear of precipitating further shoulder damage. As one can imagine, this can become quite detrimental to daily function and desired activity.

This mechanically-focused narrative poses an even larger problem when a patient is referred to rehab as a first step in order to “avoid” surgery. Nine patients were included in the qualitative study and all 9 reported a similar understanding of the problem:

Participant 3:

“It is the tendon being caught by this piece of bone and wearing it away.”

Participant 5:

“According to my doctor, I had a scan and I’ve got two extra bones … They did say there is inflammation and there’s something that’s rubbing and then every time it rubs that’s what causing me to have pain … He just said it was all swollen up and that there’s something that when it’s swollen up that’s what’s causing me the pain and that’s as much as I know.”

Participant 9:

“He said there was some impingement that could have been inflammation from irritation in the shoulder … things stopping my arm actually moving the way it should … I could just picture something just in the joint that got in the way at a certain point and was making it difficult for the socket to move in the way it should be moving.”

Since patients’ understanding of the problem was rooted in a mechanically-focused model, the expected treatment logically centered around this approach as well.

Participant 3:

“(How are we going to get this pain to go away?) By removing this piece of bone.” … “I don’t want to get to a position where it’s okay, I go back to work and it blows up again and I’m back to square one. I want it sorted you know. I said to the Physiotherapist you know, I think the only way that is going to permanently cure this is through that surgery, you know”.

Worse, this line of thinking led to patients questioning the role and efficacy of non-invasive rehabilitation treatments like exercise:

Participant 1:

“If there is a physical lump or something there, all the Physiotherapy in the world isn’t going to resolve that if that doesn’t disappear. He said that it was quite likely in my case that I might well need some keyhole surgery …” [emphasis mine]

Participant 3:

“There is a possibility, I think, I think what the [Physician] was meaning was that I could have some Physio to get the inflammation down, get the swelling down, get the muscles stronger but it’s not permanent, it’s not going to be a permanent fix, this piece of bone is still there. I can’t imagine how any amount of physio is going to shift this piece of bone which is in my shoulder.” [emphasis mine]

…

“He said we can do keyhole surgery on it and it’ll be fine. Meanwhile, he said I want you to try a couple of months of physio first before we commit to that, which puzzles me to be honest because I thought well you know, if this piece of bone is not a big job just go in there, get rid of this bit of bone, fine. So I was a bit nonplussed when I came to physio, I thought well you know, I felt a bit sorry for the guy to be honest”. Cuff 2017

Despite the previously discussed evidence showing equivalent outcomes from non-surgical treatments, the delivery of the standard mechanical impingement narrative appears to induce a substantial nocebo (latin for "I shall harm") effect upon patients. That is, their expectations of benefit from non-invasive rehabilitation treatments are worsened, a phenomenon which then tends to result in worse outcomes. Rossetini 2018 Greville-Harris 2015

Furthermore, focused attention to a supposed root "cause" may also perpetuate a narrative that lacks a level of acceptance for pain as a human experience while removing autonomy from the person. Karos 2018 This feedback may further feed into a fear-avoidance cycle along with a continuous need to investigate for a structure-based issue. Vlaeyen 2000

In regards to movement, we have no evidence for particular movements being “dangerous” for a person's shoulder. In the rehab or exercise world, we often hear that particular movements such as the upright row or behind the neck overhead press/lat-pull downs should be avoided for “shoulder health”, that one must maintain an “active shoulder”, or bench press at a 45 degree elbow angle to prevent structural damage to the shoulder musculature and associated tendons. If we instill false dichotomy-based narratives regarding shoulder movement, we continue to promote fear avoidance while perpetuating a false narrative.

Another major issue is that these supposed tissue "issues” are readily observed in the asymptomatic aging population. A 2014 article by Teunis et al, A systematic review and pooled analysis of the prevalence of rotator cuff disease with increasing age, included 30 studies of 6112 shoulders. Overall, the prevalence of abnormalities increased from 9.7% in 20 year olds to 62% in 80 year olds and older. The prevalence increased similarly regardless of symptoms or shoulder dislocation (see figure 3).

The authors conclude:

The prevalence of rotator cuff abnormalities in asymptomatic people is high enough for degeneration of the rotator cuff to be considered a common aspect of normal human aging and to make it difficult to determine when an abnormality is new (e.g., after a dislocation) or is the cause of symptoms. [emphasis mine] Teunis 2014

The authors go on to say:

Whereas many surgeons favor a ‘wear and tear’ theory, it is also possible, and in our opinion more likely, that the rotator cuff is subject to an inherent degenerative process similar to thinning and graying of the hair. [emphasis mine] Teunis 2014

A major hole was punched into the impingement narrative in 2020 when Park et al released the article, No relationship between the acromiohumeral distance and pain in adults with subacromial pain syndrome: a systematic review and meta-analysis. Curious what the acromiohumeral distance (AHD) is? It's the shortestest measured sitance between the humerus (upper arm bone) and undersurface of the acromion (the part of the shoulder blade connecting to the collar bone). The title of their review speaks for itself, but their major finding:

This systematic review demonstrated no difference in AHD, measured at 0°, 45° and 60° of shoulder abduction, between participants with SAPS and controls with no shoulder pain. This result was consistent across both athletic and the general populations.Park 2020

We also have evidence that imaging findings do not seem to correlate with future risk of shoulder pain or disability. Tran et al 2018 paper, What Imaging-Detected Pathologies Are Associated With Shoulder Symptoms and Their Persistence? A Systematic Literature Review, provides support against the idea of future problems. The authors compiled 56 studies and assessed the evidence linking imaging findings to symptoms and examined if any evidence supports development of symptoms. The authors state:

Structure-pain relationships are complex. There is the possibility that there may be no relationship between imaging findings and symptoms, and imaging findings need to be considered as part of a wider pain construct. Other factors that may be associated with musculoskeletal symptoms include age, sex, body mass index, activity, mental health, and central sensitization. Tran 2018

So 56 studies later, we haven’t learned much other than shoulder imaging doesn’t appear to tell us much about symptoms, prognosis, or treatment. And observing the trends in clinical practice, it seems to create more unnecessary problems than it solves. This obviously challenges the adage that "you'll pay for it later." Barreto et al article, Bilateral magnetic resonance imaging findings in individuals with unilateral shoulder pain, is a favorite of mine. The authors recruited individuals presenting with unilateral shoulder pain but scanned both shoulders with MRI. The findings,

Abnormal MRI findings were highly prevalent in both shoulders. Barreto 2019

An even more interesting finding from this study, the authors had a shoulder surgeon and radiologist review the images to see how often they agreed with one another regarding findings.

Agreement between the musculoskeletal radiologist and shoulder surgeon ranged from slight to moderate (0.00-0.51) Barreto 2019

This finding demonstrates the subjective nature of interpreting imaging findings, something folks may not have considered. Radiological reports, in this context, are often presented as matter of objective fact, but that clearly isn't the case as we've seen similar findings in low back research. Herzog 2017

Where do we go next?

If we’re going to dispose of subacromial impingement syndrome, how should we instead label these painful shoulders? There is now a push to shift the terminology to things like Subacromial Pain Syndrome (SPS), Rotator Cuff Syndrome, or Rotator cuff-related shoulder pain.

Dierks et al published a 2014 review, Guideline for diagnosis and treatment of subacromial pain syndrome: a multidisciplinary review by the Dutch Orthopaedic Association. They define SPS as,

….all non-traumatic, usually unilateral, shoulder problems that cause pain, localized around the acromion, often worsening during or subsequent to lifting of the arm. Dierks 2014

The authors propose that the umbrella term Subacromial Pain Syndrome encompass the following current diagnoses: bursitis, tendinosis calcarea, supraspinatus tendinopathy, partial rotator cuff tear, biceps tendinitis, or cuff tendon degeneration. Dierks 2014

Zadro et al recently assessed how six labels influence participants' healthcare expectations, for example the perceived need for imaging, injections, second opinion, specialist referral, and surgery. These labels included:

• subacromial impingement syndrome

• rotator cuff tear, bursitis

• rotator cuff–related shoulder pain

• shoulder sprain, and

• episode of shoulder pain

The authors found that participants who received the diagnostic label of rotator cuff tear had a slightly higher desire for surgery and those receiving subacromial impingement syndrome had an increased perceived need for imaging. Zadro 2021

I'm a biased fan of the label general shoulder pain to minimize assigning a specific physical tissue issue. This label shifts focus more towards the path ahead and pursuing valued activity goals vs being stuck on a specific tissue issue to try and fix, which isn't necessary typically. This line of thinking is one of the largest differences between the biomedical versus biopsychosocial approaches to pain treatment.

Prognosis > Diagnosis

Regardless of the selected diagnostic label, the prognosis in these scenarios likely matters more than the specific structural diagnosis. Clinicians like to supply labels for patient symptoms in order to neatly place these “problems” into biomedical boxes. We can then intervene upon these boxes with specific treatments to “fix” the patient. There are two major issues with this approach:

1. We have more evidence demonstrating what are likely not problems than what are problems, and

2. This approach leaves out a huge part of the picture as it relates to treating the person, rather than treating the bursa, the tendon, or the joint; ultimately stigmatizing the person. Cohen 2011

With that said, how should we appropriately assess this issue clinically? According to Dierks et al:

No single test is sufficiently accurate to diagnose SPS. The inter-rater reliability of the most common tests varies greatly. Dierks 2014

We see this statement further supported by a Cochrane Review: Physical tests for shoulder impingements and local lesions of bursa, tendon or labrum that may accompany impingement,

There is insufficient evidence upon which to base selection of physical tests for shoulder impingements, and local lesions of bursa, tendon or labrum that may accompany impingement, in primary care. The large body of literature revealed extreme diversity in the performance and interpretation of tests, which hinders synthesis of the evidence and/or clinical applicability. Hanchard 2013

And based on the above discussion, diagnostic imaging like X-ray or MRI is likely not beneficial in atraumatic shoulder pain situations either, given the increasing likelihood of finding a supposed “abnormality” on imaging as we age. If you are following the theme of this article, it should be apparent that the specific tissue “abnormality” is less important for prognosis and outcomes.

So, what is relevant for the prognosis of general shoulder pain? According to Dierks et al, one of the main focal pints is psychosocial factors.

Dierks states,

Psychosocial factors appear to have a greater association with the course and prognosis of chronic shoulder pain (> 3 months) than with that of shorter-term shoulder pain (< 6 weeks). [empahsis mine] Dierks 2014

Psychosocial factors are important, given our lack of evidence for strong correlations to structural issues. A recent longitudinal study on prognostic factors related to physiotherapy outcomes identified 4 relevant factors that led to better outcomes (less pain and disability):

1. Lower baseline disability

2. Patient expectation of “complete recovery” vs “slight improvement” due to physiotherapy treatment (which, notably, can be influenced by our words & narratives)

3. Higher pain self-efficacy

4. Lower pain severity at rest Chester 2016

Two of these points have a substantial base of supporting evidence. A prior systematic review discusses the relationship between a person’s self-efficacy and effects on prognosis for chronic musculoskeletal pain. The authors define self-efficacy as “the personal confidence to carry out an activity with the aim of successfully achieving a desired outcome.” Martinez-Calderon 2018

The authors conclude:

Our results suggest that higher [self-efficacy] levels are associated with greater physical functioning, physical activity participation, health status, work status, satisfaction with the performance, efficacy beliefs, and lower pain intensity, disability, disease activity, depressive symptoms, presence of tender points, fatigue and presenteeism. Martinez-Calderon 2018

How do we instill and bolster self-efficacy in patients? Most importantly, we must ensure we are not creating unnecessary issues for us to fix, as this removes the locus of control and autonomy from the individual and creates dependency on the clinician. Instead, clinicians should guide the path to patient goals via education and demonstration of how they can take care of themselves. We should promote narratives of resilience instead of vulnerability. Esteve 2017

Setting expectations goes hand-in-hand with this approach. As described above, our narratives directly influence patient beliefs, which then influence treatment outcomes. We must ensure we are setting appropriate and realistic expectations for the issue being addressed as well as for treatment. For a detailed discussion of setting expectations, see Bialosky et al and Geurts et al.

When it comes to treatment, education appears to be the best bet for helping patients reach their goals, followed by exercise. Now, there is certainly a chance that the benefits of exercise, much like surgery, are primarily mediated by placebo-like contextual effects. Or perhaps exercise just entertains the clinician and patient while natural history and regression to the mean occur over time. However, to quote a recent JOSPT editorial by Lewis:

… proponents of evidence-based practice would advocate that if there are 2 interventions of equal clinical effectiveness (even if the basis for that outcome is uncertain), then the choice of the economically competitive treatment should dominate that of the more expensive intervention, allowing the finite resources to be directed in a more appropriate manner. Furthermore, activity- and exercise-based interventions have significant and important health benefits. Lewis 2018

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Recap

Although many practitioners are happy to provide confident, superficially plausible-sounding explanations for pain, we aren’t entirely sure why certain people develop shoulder pain. To date, subacromial impingement syndrome remains a poor narrative based on outdated information. However, we now have a better understanding of the need to de-emphasize rigidly biomedical narratives that are overly focused on supposed structural/mechanical “abnormalities”, as we have little supportive data for pathoanatomical or kinesiopathological causes. We do have good quality research evidence on efficacious ways to mitigate the risk for development of symptoms by focusing our attention on two primary areas, which we will discuss in further detail in the next section:

1. Psychosocial coping skills

2. Load / Fatigue Management

Additionally, attempting to answer the question of why someone became symptomatic may not be productive, as it elicits further unnecessary hyper-vigilance to a perceived problem rather than a solution. We need to shift our language away from blaming specific tissue issues and reframe towards person level approaches, while collaborating on a path forward towards valued life activities. For now, our best bet is to minimize unnecessary, invasive, and costly procedures while instilling confidence in patients and their ability to move and self-manage without unnecessary false biomedical narratives. The next section will discuss internal impingement in the overhead athlete.

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Another lesser-known type of impingement, known as “internal” impingement, is diagnosed in overhead and throwing sports like baseball, racket sports, volleyball, water polo, etc. In a similar fashion to external impingement, this is another situation that has been historically pathologized, labeled as a problem that needs to be fixed. But is this really the case? Or, as we have seen in other contexts, could it represent normal activity-related adaptation that gets blamed for pain and dysfunction in the athlete? Let’s examine this topic more closely.

Internal Impingement - Here we go again

Imagine the late-cocking phase of pitching, with the arm abducted and externally rotated (above image). In this phase of the throwing movement, the greater tuberosity of the humerus is thought to come into contact with the posterior-superior glenoid rim. Spiegl 2014 The assumed purpose of this mechanical phenomenon is to limit excessive external rotation of the shoulder. Some argue that repeated bouts of overhead throwing movements can lead to “internal impingement” of the labrum and rotator cuff, between the humeral greater tuberosity and glenoid rim (see figure 4)

Presentation

It is hypothesized that as a result of this “impingement,” these athletes develop symptoms such as shoulder pain, dysfunction, and decreased performance. Spiegl describes the clinical presentation as

nonspecific and unyielding … Most athletes will present with chronic, diffuse, posterior shoulder pain that is exacerbated by activities requiring abduction and external rotation. Spiegl 2014

The larger issue here is that shoulder symptoms are complex and multifactorial; but as is often the case, the narrative surrounding symptomatic internal impingement often becomes purely mechanical in nature. The clinical examination typically involves evaluation of internal and external rotation ranges of motion, as well as orthopedic tests like the “posterior impingement sign”. If the exam reveals an apparent range of motion deficit with a positive posterior impingement test (i.e., posterior shoulder pain while placing the shoulder in late-cocking phase position), then radiologic imaging is typically obtained to evaluate for pathology.

As usual in musculoskeletal practice, symptoms are being assigned to a specific structure/tissue without recognizing the complex, multifactorial aspect of the patient presentation. Additionally, we can’t ignore the possibility that what is seen on imaging may represent normative sport-specific adaptations (more on this later) or common age-related incidental findings that are being inappropriately labeled for symptoms.

Many clinicians and coaches argue for pre-participation screening and assessment of the shoulder of overhead athletes to prevent such “injuries”, despite a 2018 review by Asker et al finding little support for this approach. The authors found limited evidence on any currently researched risk factor for shoulder injury, and even less evidence on preventing injuries in this cohort.

Their conclusions:

All investigated potential risk factors for shoulder injury in overhead sports had limited evidence, and most were non-modifiable (eg, sex). There is also limited evidence for the effect of shoulder injury prevention measures in overhead sports. Asker 2018

The usual imaging culprits attributed to this symptom presentation in overhead athletes include the following:

• Bennett’s Lesion (posteroinferior glenoid exostosis)

• Anterior glenohumeral laxity

• Glenohumeral Internal Rotation Deficit (GIRD)

• SLAP (superior labrum anterior to posterior) tears due to “peel-back mechanism” leading to “pseudolaxity”

• Scapular malposition resulting in “SICK scapula syndrome” (prominent inferomedial border of scapula, coracoid tenderness, and scapular dyskinesis, which is considered an overuse syndrome that leads to increased risk for SLAP tears and internal impingement. See our previous discussion on scapular dyskinesis.)

• Humeral and glenoid retroversion (“posterior shift” of structures)

This list continues to grow as we approach a complex pain-based issue through a structural biomedical lens. Overall, there remains a lack of agreement on pathoanatomical or kinesiopathologic shoulder issues relevant to internal impingement. Spiegl et al state:

Owing to the large body of evidence suggesting various factors that may be involved with the development of symptomatic internal impingement and its corresponding pathologic lesions, it is most likely a complex, multifactorial process that has yet to be completely elucidated. Further research is needed to more clearly demonstrate the association between the various pathophysiological adaptations in the throwing shoulder with the pathologic lesions seen in patients with symptomatic internal impingement. [emphasis mine] Spiegl 2014

A case for sport-specific adaptations

Labeling tissue changes as pathological in these scenarios is a typical oversimplification of a complex, multifactorial issue. For example, Pennock et al’s study Shoulder MRI Abnormalities in Asymptomatic Little League Baseball Players recruited 23 asymptomatic (no pain or disability) male little league baseball players (average age 11.4 years) and assessed range of motion, strength, and stability of their arms. Following physical examination, subjects underwent MRI and ultrasonography of both shoulders. Participants with a prior history of baseball-related shoulder pain/injury were then compared to participants without such issues. Further comparison was performed between players with dominant-arm MRI abnormalities versus those without.

Physical examination revealed asymmetrical shoulder range of motion between dominant and non-dominant arms. Specifically, internal rotation (See figure 4)was decreased by 7 degrees in the dominant arm and up to 10 degrees in 26% of the included players. 5 degrees of retrotorsion of the dominant arm vs nondominant arm was also identified.

The MRIs revealed 17 asymmetric “abnormalities” in dominant shoulders of 12 players (52%). 4 out of the 12 players had multiple abnormalities. The non-dominant arm MRIs had 2 abnormalities (labral tears). Overall, there was a 6-fold higher rate of “abnormalities” in the throwing arm of the athletes. The most common abnormalities included:

• Edema/widening of proximal humeral physis (5 players)

• Labral tear (4 players)

• Partial rotator thickness tear (4 players)

• Hypertrophy of acromioclavicular joint capsule (2 players)

• Subacromial bursitis (1 player)

• Cystic change of greater tuberosity (1 player)

Interestingly, players who were year-round players or single-sport athletes were more likely to have MRI abnormalities. Players with one of these two risk factors had a 71% chance of MRI abnormality, and players with both risk factors had a 100% chance of an MRI abnormality.

The argument could be made that these sorts of imaging findings increase the risk of developing symptoms in the future. But so far, that doesn’t appear to be the case for most shoulder imaging findings either (recall our discuss of Tran et al review above). The argument can also be made that the reported imaging findings are actually sport-specific adaptations that we label as pathologic using biomedical terminology on radiology reports. We also have evidence of similar findings in asymptomatic professional baseball players. Del Grande et al found,

In asymptomatic baseball pitcher draft picks, 3-T MRI frequently shows abnormalities involving rotator cuff tendons, the coracohumeral, inferior glenohumeral, labrum, and osseous structures. Del Grande 2016

Since we can observe these findings as early on as in Little League players, as well as later in baseball careers, these may very well represent adaptive changes for the demands placed upon these shoulders. Further, baseball isn’t the only overhead sport where we find asymptomatic alterations on shoulder imaging, either. We have similar studies for:

• Elite level volleyball players

• Elite level tennis players

• Division IA collegiate volleyball players, swimmers, and gymnasts

As well as a 5 year follow-up on shoulder imaging in asymptomatic overhead athletes. Connor et al examined MRIs of asymptomatic overhead athletes and compared findings of dominant vs non-dominant sides. Athletes were then contacted again 5 years later and asked if they had developed shoulder symptoms, were still playing their sport, or if they decided to retire related to a shoulder issue. The authors’ findings 5 years after imaging:

None of the athletes interviewed 5 years later had any subjective symptoms or had required any evaluation or treatment for shoulder-related problems during the study period. Connor 2003

Instead, interviewed participants remained asymptomatic while still playing their respective sport. The authors conclude,

We found a high incidence of clinical false-positive MRI findings manifested as partial- or full-thickness rotator cuff abnormalities (40%) and Bennett’s lesions (25%) in dominant shoulders. Similar findings were not found in these athletes’ nondominant shoulders. Importantly, shoulders with these MRI abnormalities continued to be asymptomatic at the 5-year follow-up. Connor 2003

Maybe, there is a “natural history” effect to these MRI findings? Schär et al set out to answer this question with their article, Many Shoulder MRI Findings in Elite Professional Throwing Athletes Resolve After Retirement: A Clinical and Radiographic Study. The authors completed MRIs on two separate groups.

The first group received initial MRI scans of their throwing and non-throwing shoulders, and imaging was repeated six years after their retirement from sport. A second group who were not initially scanned were recruited and underwent bilateral shoulder MRI scans 15 years after their retirement from sport. A primary finding,

Our data suggest that findings of the throwing shoulder like partial rotator cuff tears, bony cysts and ganglions do not progress after retirement, and sometimes they resolve. Because of this and because many MRI changes correlate poorly with clinical symptoms, the indication for surgical treatment of these findings should be questioned very carefully. Schär 2018

So what matters with this population?

Check out Figure 5.

Hopefully we now have a better understanding for the need to deemphasize rigidly biomedical narratives that are overly focused on structural and/or mechanical “abnormalities”. We have little supportive data on a pathoanatomical or kinesiological reason for symptomatic internal impingement. However, we have good quality research evidence on efficacious ways to mitigate the risk for development of symptoms in the overhead athlete.

We should likely begin by mitigating early sport specialization (recall the data on year-round, single-sport players cited above), given that symptomatic internal impingement appears to be an overuse “injury” to the shoulder. We have further support for this line of thinking via a recent systematic review and meta-analysis by Bell et al. The authors found athletes who were highly specialized were twice as likely to sustain an overuse injury when compared to athletes with low specialization. Analysis also revealed risk for overuse injuries increased in a stepwise fashion with increasing levels of specialization. Bell 2018 Early sport specialization goes hand-in-hand with load and fatigue management. Jones et al discussed the influence of training load and fatigue on athlete injury and illness. The authors recommend training load and fatigue should be monitored and altered accordingly. Fatigue is defined as “the decrease in the pre-match/baseline psychological and physiological function of the athlete.” Jones 2017

They go on to state, “An accumulation of fatigue can result in overtraining, which has a significant negative impact on performance.” Jones 2017 “Training load” is multifactorial, but includes variables such as session Rate of Perceived Exertion (sRPE), volume, intensity, and frequency of activity. For an in-depth review of the supportive research on the strong associations between training load and injury, see Eckard et al. Additionally, strength training should be incorporated as a mechanism of building resilience and one factor in injury risk reduction for athletes. Lauerson 2018 Finally, likely most importantly we should ensure athletes have adequate psychosocial coping skills in place to manage life and athletic stressors. Ivarsson 2016

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Recap

In closing, symptomatic internal impingement describes a non-traumatic pain-based issue that has little evidence supporting a clear structural pathology. The findings on radiologic imaging once a person becomes symptomatic likely represent sport and age-specific adaptations, rather than primary drivers of patient symptoms. Furthermore, we have strong evidential support for ways to mitigate the development of symptoms. However, once symptomatic, time can be utilized educating the person on pain, self-management strategies, and guiding through a scaffolded-activity plan to return to activity. Our final section to the shoulder guide will cover rotator cuff tears. We've seen a 200% increase in rotator cuff surgical rates in USA and Europe, but is this increase warranted? Littlewood 2018

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Recall from our introduction, the rotator cuff is a set of four muscles around the glenohumeral joint including the supraspinatus, infraspinatus, subscapularis, and teres minor (see figure 2).

These muscles all originate from the scapula, insert at various points on the humerus, and serve multiple coordinated functions including abduction, adduction internal rotation, external rotation, and stabilization of the arm. Each muscle is considered to have its own unique action on scapulohumeral movement (sometimes described as scapulohumeral rhythm, as discussed above). Unfortunately, the cuff muscles are often viewed as both the source and the answer to the majority of shoulder pain and dysfunction. In addition to “impingement”, pathology of the rotator cuff muscles including tears and tendinopathy are among the common narratives used to explain shoulder pain and dysfunction. We’ve already had an extensive discussion on the lack of evidence supporting such a reductionist approach to shoulder pain; however, given the persistence of these ideas in the rehab world and the general public, bear with us as we tackle rotator cuff tears next.

So, why do individuals select shoulder surgery?

A recent qualitative study by Malliaras et al sought to answer this question. Fifteen individuals who had rotator cuff tendon repair with or without subacromial decompression for rotator cuff related shoulder pain were interviewed to understand decision making to elect surgical intervention. The participant's ages ranged from 34 - 71 years old, and duration of symptoms were from 6 to >52 weeks.

The authors identified 6 themes leading to the decision to undergo surgery. Each theme is presented below followed by a participant quote.

• Theme 1 - Needing to get it done: "it was necessary to remedy the dire situation". A participant stated,

I had the inability to operate as a normal human being in everyday life. Even taking clothes off, putting bras on and off, washing your hair. In fact, I used to have shoulder length hair. I’ve had it all cut off for the whole idea of being able to wash my hair with ease.

• Theme 2 - Non-surgical treatment experience: “I knew that I’d done all I could”.

I tried physio for a while. Then I decided to do a cortisone injection, which helped a bit but then I went traveling, lifted a heavy suitcase and the pain came back …so I went to a surgeon.

• Theme 3 - Mechanical problem: “Physio’s not going to repair a torn tendon”

Well, look, people have said afterwards that I should have done [more] physio beforehand and that sort of thing and maybe that was an option but physio’s not going to repair a torn tendon.”

you must be in a lot of pain, because there is a tear, and it’s virtually completely off your bone.’ He [surgeon] said, ‘You’re going to have to operate.”

• Theme 4 - Trust in medical professionals “if they told me that I needed to swallow a thousand spiders, I would have done it.”

I had a lot of faith in the surgeon because I think was the fourth who I know who he did and they all reckon he’s a legend.

• Theme 5 - Varied information sources required “Dr Google played a big part in it”

The surgeon gives you their package of information. My physio had his own package of information… But being in the health care profession Dr Google played a big part in it.

• Theme 6. Organisational barriers “it was absolutely useless, my insurance”

This isn’t a situation where I’m getting a dint in my old bomb car fixed up. This is my left shoulder. So really in terms of quality of life, it’s a little bit priceless…. I owe myself something at sixty-three, so that I’ve got a quality of life.

The authors summarize their findings,

A commonly held belief among participants in this study was that surgery was inevitable because of mechanical damage or tears in their rotator cuff tendons. The relationship between imaging abnormality and their symptoms was not questioned by many of the interviewees. Health professionals often confirmed the view that abnormalities on imaging may require surgery, which left patients with the sense that there was no option. Malliaras 2021

It's probable if you are reading this guide as a healthcare professional you've said or heard others say similar statements to patients. If you're someone who has dealt with chronic shoulder pain, then perhaps you've heard similar statements or used the same rationalization to elect shoulder surgery. Importantly, we need to understand and accept our narratives about pain bidirectionally influence expectations and management strategies, meaning, on the part of the healthcare professional and patient. Many participants held strong views that their pain experience was primarily mechanically driven based on clinician narratives and imaging findings. Additionally, they had overwhelming trust in medical professionals, specifically surgeons, their opinions, and reputation; while some participants were critical of non-surgical health professionals. Many also turned to the internet for advice or anecdotal re-assurance via word of mouth from others’ having similar surgery. Belief formation is complicated and multifactorial, but healthcare professionals are often viewed as a shining beacon in an individual's pain storm; providing guidance on the appropriate path affording the least amount of obstacles and safe arrival at the destination. Given the prevalence of misinformation on shoulder pain and over-reliance on surgical intervention, we will further explore the evidence in the context of rotator cuff tears.

Rotator Cuff “Degeneration”: The “Gray Hair” of the Shoulder

A muscle tear sounds really bad, right? But if we are going to call something a problem, its prevalence should, to some extent, differ between those who experience symptoms or complications, and those who don’t. Recall above, Teunis et al found a progressively higher prevalence of findings of rotator cuff alterations in the aging population who were asymptomatic (no pain or disability).

This continues to cast doubt upon the biomedical narratives and pathologizing of rotator cuff tears. However, given how often this diagnosis occurs, we will discuss how the issue is usually framed in healthcare.

“Traumatic” vs. “Degenerative” Tears: A Case of Uncertainty

When a tear of the rotator cuff musculature is diagnosed, a dichotomy of “degenerative” (non-traumatic) or “acute” (traumatic) is usually applied. “Traumatic tears” are typically diagnosed when shoulder pain is attributed to a specific event that is assumed to be sufficiently traumatic to tear a cuff muscle/tendon. In contrast, “degenerative” tears are diagnosed when a preceding traumatic incident can’t be identified. Why does this labeling system matter? Because the plan of care is typically altered based on the label applied. If the tear is deemed “non-traumatic”, then a round of so-called “conservative” management (i.e., rehabilitation) is typically recommended prior to considering more invasive treatments like surgery. However, if the tear is labeled “traumatic”, then surgical intervention is likely to be recommended as soon as possible, although exactly how soon is debatable. (Chris Littlewood makes a compelling argument regarding the controversy around rotator cuff tears and their treatment in his editorial, The enigma of rotator cuff tears and the case for uncertainty). The flaw with this diagnostic approach is the difficulty in determining whether a cuff tear is actually “new” and associated with the trauma, or whether it was already present, asymptomatic, and undetected until the clinical evaluation for new shoulder pain. But if we follow this line of thinking, we must have good evidence validating the need to surgically intervene on a rotator cuff tear … right?

As it turns out, we don’t.

Surgical Repair for Rotator Cuff Tears

From the traditional biomedical perspective, if we examine a painful shoulder and find a torn rotator cuff muscle, repairing the tear should result in prompt resolution of pain or dysfunction. But, what does the evidence on surgery for rotator cuff tears tell us?

A 2016 meta-analysis by Ryösä et al synthesized data from 3 randomized controlled trials including a total of 252 participants comparing surgical versus conservative management outcomes. It should be mentioned that this is a small number of studies and participants on which to perform a meta-analysis, and there was a moderate level of heterogeneity in the data. These factors should temper our confidence in the conclusions at this point in time. After analysis, the authors concluded:

There was no clinically significant difference between surgery and active physiotherapy in 1-year follow-up in improving Constant score or reducing pain caused by rotator cuff tear. As physiotherapy is less prone to complications and less expensive than surgery, a conservative approach is advocated as the initial treatment modality to rotator cuff tears. Ryösä 2016

In 2021, Longo et al conducted a systematic review and meta-analysis comparing conservative management and surgical intervention for rotator cuff tears while assessing two year outcomes. The authors included 6 articles in total with 339 participants. Interestingly, the included studies were by the same authors included in the 2016 review. The authors failed to find a meaningful difference between conservative and surgical management for pain and function at two years. Longo 2021

In a newly published review, Fahy et al sought to build on this data by comparing the effects of exercise to other interventional options, inclusive of conservative, control, and surgical. In total, five trials were included with 297 participants, average age of 66 years old. Three trials compared exercise to another non-surgical intervention, and two trials were included comparing exercise to surgery. However, both of those surgical trials were included in the above mentioned reviews, demonstrating no new data comparing exercise to surgery since 2016.

Author's primary conclusion:

Based on the available evidence exercise is as effective as surgery for improving quality of life, disability and pain for L-MRCTTs [large to massive rotator cuff tendon tears] but the conclusion is based on low certainty of evidence The completeness of content reporting of exercise interventions in the management of people with L-MRCTTs is extremely poor. Fahy 2022

In a larger study, Khatri et al examined the natural history of full-thickness, symptomatic rotator cuff tears by reviewing 57 randomized controlled trials involving 4542 total participants. The studies were grouped into three categories based on interventions:

1. Surgical repair,

2. Acromioplasty alone,

3. Non-operative treatment.

The authors’ findings:

There was an overall improvement in all arms from baseline for studies reporting the Constant score. When differences between operative and nonoperative arms were explored, this effect was sustained, with all study arms showing positive change. Treatment response in all outcome measures … showed an improvement in functional outcomes regardless of treatment intervention applied. Studies that followed up patients at multiple time points indicated an improvement in outcome in the first 12 months, after which the rate of improvement stabilized. This pattern was consistent irrespective of treatment type given (primary repair, acromioplasty only, or nonoperative intervention). Khatri 2018

Since it seems we can often accomplish similar outcomes regardless of operative or non-operative treatment for rotator cuff tears, we should seriously question the efficacy and justification for such invasive procedures. Furthermore, if we can accomplish similar outcomes with two different treatment approaches, then the less risky option should be the treatment of choice. The authors conclude:

We show that patients with symptomatic full-thickness rotator cuff tears demonstrate a consistent and considerable response to treatment, even with nonoperative management. The largest improvement occurs in the first 12 months, after which the response stabilizes. When the treatment effect of invasive surgery is assessed, consideration must be given to the natural history of patients with rotator cuff tears to improve over time with nonoperative care as well. Khatri 2018

Despite the popularity of the biomedical narrative regarding rotator cuff tears, at this point it appears the type and severity of a tear have little, if any, bearing on treatment selection and outcomes. This data also implies natural history has been under-appreciated given the significant improvement in outcomes over time regardless of intervention. Major takeaway, the above research strongly contradicts the traditional structurally-focused biomedical approach

Should we be worried about tear progression?

Another common argument is the need for surgical intervention to prevent tear progression over time. Despite this being an overly biomedical and reductionist view, how concerned should we be about tear progression?

Kwong et al performed a systematic review of the literature regarding the natural history of non-operative rotator cuff tears in symptomatic and asymptomatic populations. The primary outcome was progression of tear size of at least 5 mm as measured by MRI or ultrasound. They identified 8 studies meeting their inclusion criteria (4 on symptomatic individuals and 4 on asymptomatic individuals) that included a total of 411 tears (255 asymptomatic and 156 symptomatic). The authors found 40.6% of asymptomatic tears progressed over 46.8 months and 34.1% of symptomatic tears progressed over 37.8 months. The average progression per month was .85% and 1% for asymptomatic and symptomatic groups respectively. Of note, neither finding met a statistically meaningful difference between groups. Kwong 2019

In other words, both asymptomatic and symptomatic tears progressed at similar rates, and don’t appear to progress significantly during 2-5 years. This finding further muddies the water on why shoulders become symptomatic. Admittedly, we don’t know, and it doesn’t appear to be as strongly correlated with the presence or severity of a tear as previously thought. It further questions the necessity of surgical intervention based on the narrative of mitigating tear progression for fear of developing symptoms. The authors go on to state:

This finding may reflect the fact that pain (i.e., symptoms), as the independent variable between the 2 groups in this study, remains a subjective measure of disease whereas the underlying tear characteristics (e.g., progression and size) and their contribution to nociception remain unclear. Kwong 2019

What happens if the scalpel is put away?

So how do patients do over time without surgery? Boorman et al sought to answer this question in their study, The rotator cuff quality-of-life index predicts the outcome of nonoperative treatment of patients with a chronic rotator cuff tear. The authors studied the outcomes of a physiotherapy program for chronic (i.e., symptoms greater than 3 months) full-thickness rotator cuff tears in 93 patients. Patient outcomes were categorized as “success” versus “failure” based on non-operative treatment. In other words, if the patient and surgeon ultimately elected to have surgery after 3 months of physiotherapy, then the case was deemed a “failure”. The results showed that 75% of patients were classified as having a successful outcome at 3 month mark. On the other hand, 23 patients (25%) were considered as “failed” nonoperative treatment, since they went on to undergo rotator cuff surgical repair. More interestingly, the two year follow-up data illustrate the nuances here:

During the two years of follow-up, ten patients crossed over to the opposite treatment. Four patients who had originally been classified as having had a treatment failure experienced subsequent improvement and canceled their scheduled surgery. Six patients originally classified as having had a successful treatment experienced increased symptoms in the affected shoulder and underwent surgery. Four of the latter six patients fell and reinjured the shoulder, one injured the shoulder lifting a suitcase into the trunk of a car, and the sixth patient attributed her need for surgery to the daily struggle of dressing with compression stockings. Boorman 2014

Note that only six out of the 70 successful cases had worsening symptoms and underwent surgery over the 24 month follow-up period. The authors report that “these results suggest that a successful result at three months is most often durable over time.” Boorman 2014

Fortunately, the authors also followed up on study participants at 5 years. They report:

Between the 2- and 5-year follow-up periods, only 3 of 64 patients who had previously been defined as having a successful outcome became more symptomatic and underwent surgical rotator cuff repair. Of these 3 patients, 2 experienced a gradual worsening over time whereas 1 was doing very well until an errant golf swing significantly exacerbated his symptoms. Boorman 2018

Overall, outcomes were not different between the successful versus failed group at 2 years and 5 year follow-up points. Therefore, the authors conclude:

Nonoperative treatment is an effective and lasting option for many patients with a chronic, full-thickness rotator cuff tear … While some clinicians may argue that nonoperative treatment delays inevitable surgical repair, our study shows that patients can do very well over time, no matter whether treated operatively or nonoperatively. [emphasis mine] Boorman 2018

It appears that the prevalence rate of rotator cuff tears increases with aging, and even if we deemed the tears as necessitating intervention, surgery doesn’t appear to be the best option for many cases. So if not surgery, then what should we be doing for patients presenting with shoulder pain who have been identified to have a rotator cuff tear?

Shoulder Injections

Injections are a commonly offered therapy in orthopedic and sports medicine clinics. Typical injections are described to patients as a combination of “numbing” medicine (local anesthetic) with an “anti-inflammatory” medicine (corticosteroid). But, does research support the popularity?

A recent review of 13 studies by Cook et al examined the short term (<3 months), mid-term (3-12 months), and long term (>1 year) outcomes of injection therapies. They looked at studies of corticosteroid injections with/without local anesthetic vs. local anesthetic alone, in order to clarify the specific effects of corticosteroids on outcomes.

For the 12 studies looking at short-term outcomes (<3 months):

• 5/12 studies (4 of which had high risk of bias) favored corticosteroid injections.

• 3/12 studies (1 of which had high risk of bias) showed improvements from corticosteroid injections in the initial 4-6 weeks, but no significant difference was observed at 12 weeks.

• 4/12 studies (3 of which had high risk of bias) demonstrated no significant difference in short-term outcomes between the two types of injection therapy at any time point.

For the 5 studies looking at medium-term outcomes (3-12 months):

• 2 studies (with high risk of bias) showed a significant difference in outcomes supporting corticosteroid injections.

• 1 study (with high risk of bias) favored local anaesthetic injections for pain mitigation.

• 2 studies (with low risk of bias) showed no significant difference in mid-term outcomes between the two types of injection therapy.

For the 2 studies looking at long-term outcomes (>1 year):

• 1 study (high risk of bias) favoring corticosteroid injections

• 1 study (low risk of bias) demonstrating no significant difference between injection groups.

The authors summarizing their findings:

In summary, [corticosteroid] injections may have better short-term results than anaesthetic-only injections in the first 8 weeks. There does not appear to be any convincing evidence from the studies of low or high risk of bias that [corticosteroid] injections confer additional benefit over anaesthetic-only injections after this time point. Cook 2018

Of note, many of the included studies had multiple concurrent interventions (e.g., exercise and NSAIDs) which may have affected the observed outcomes. It’s also worth emphasizing the important placebo-like contextual effects of injection therapies. These effects may include the theatrics of an intervention injected directly to the perceived “source” of pain, and the clinician narrative to the patient the syringe contains a potent combination of a numbing medication and long-acting anti-inflammatory drug.

Most importantly, we need more data clarifying the risks versus benefits of corticosteroid injections in order to assess utility and efficacy. We may be dangling the carrot of pain relief in front of patients without a good grasp on the risks of corticosteroid injections compared to their short-term benefits. The authors end the discussion with a call to action:

Future research is needed that compares injections of CS, local anaesthetic, saline injections, needle only (for the mechanical effect), other products (eg, hyaluronate sodium) an advice only group, true placebo and a control group (to map natural history). Cook 2018

We actually do have emerging evidence questioning the efficacy of corticosteroid injections, see:

1. Increasing Numbers of Shoulder Corticosteroid Injections Within a Year Preoperatively May Be Associated With a Higher Rate of Subsequent Revision Rotator Cuff Surgery and

2. Preoperative Injections May Be an Iatrogenic Cause of Reoperation After Arthroscopic Rotator Cuff Repair.

Exercise

As we discussed above, exercise is demonstrating equivocal outcomes to other riskier interventions, such as surgery. To further support this point, we can examine the systematic review by Jeanfavre et al which assessed the efficacy of exercise for full-thickness rotator cuff tears. The authors included studies on adults over 18 who underwent exercise therapy alone or in combination with other non-operative interventions for their tears. Outcomes included 1) pain, 2) range of motion, 3) strength, and 4) function of the affected shoulders.

The authors included 39 studies on a total of 2,010 shoulders from 1,913 subjects. Ages ranged from 23 to 80, with a mean of 64.1 years. Of the included shoulders, 1,462 were associated with a mechanism of injury, while 1,192 were deemed atraumatic. The duration of symptoms varied from 1 day to 5.5 years. Tear size was provided on 1,155 shoulders.

Findings from participants who did not receive shoulder surgery:

1. Pain – 790 / 923 (85%) shoulders reported improvement in pain, versus 133 shoulders that did not improve or not to a “satisfactory” level.

2. Range of Motion – 1140 / 1369 (83%) shoulders reported improvements in range of motion versus 229 shoulders that did not improve or not to a “satisfactory” level.

3. Strength – 514 / 598 (86%) shoulders reported improvement in strength versus 84 shoulders that did not improve or not to a “satisfactory” level.

4. Function – 1366 / 1610 (85%) shoulders reported improvements in function versus 217 shoulders that did not improve or not to a “satisfactory” level.

It is worth noting that there was large variability in the exercise therapy offered. Programs included: strengthening, range of motion, stretching / flexibility, activity modification/education, home exercise program, manual therapy, heat/cold modalities, and postural interventions. The heterogeneity in exercise therapy is a major issue in accurately assessing the efficacy of exercise therapy, and ensuring appropriate rehabilitative programming is being utilized. We therefore need more well-conducted studies to assess what type and dose of exercise therapy is sufficient to reach clinically meaningful outcomes for patients.

The overall conclusions of the authors:

The results of the current systematic review of the current literature provided few high-quality randomized control trials and a predominant number of observational studies, indicating GRADE B Recommendation (moderate strength) to support the use of [Exercise Therapy] in the management of [Full Thickness Tears]. There is substantial evidence to support the use of exercise therapy as first line management, especially in individuals >60 years of age with chronic, degenerative FTT. Future efforts should focus on coming to a consensus regarding exercises and interventions that are most effective in the conservative treatment of individuals with full thickness rotator cuff tears. [emphasis mine] Jeanfavre 2018

What about Psychosocial factors?

Coronado et al completed a systematic review to examine whether certain psychosocial factors are associated with patient-reported outcome measures at initial consultation and post-treatment for patients with rotator cuff tears. Examples of psychosocial factors include: emotional / mental health, psychologic distress, anxiety, depression, and fear avoidance.

Ten studies met the authors’ inclusion criteria (5 cross-sectional and 5 prospective cohort studies), totaling 1410 participants (age range from 46-62 years). The authors conclude:

The results of this review suggest that psychosocial factors, namely emotional or mental health, are associated to a weak to moderate degree with initial function or disability and pain in patients seeking operative treatment for rotator cuff tears, whereas expectation was the only factor associated with postoperative patient-reported outcomes. However, these findings were only observed in at most three studies. The lack of well-designed prospective studies in this area limits conclusions about the potential prognostic value of psychosocial factors. Coronado 2018

Overall, we need more data in this area. The authors did not find any studies assessing the association of psychosocial factors on patient outcomes in the context of non-operative treatments for rotator cuff tears, or among patients not actively seeking treatment at all. The authors also failed to find any cross-sectional data examining the association of fear-avoidance beliefs and pain catastrophizing on patient-reported outcomes. However, above we discussed an article by Chester et al, demonstrating how four specific psychosocial factors led to better outcomes related to physiotherapy for patients dealing with shoulder pain: 1) lower baseline disability, 2) patient expectation of “complete recovery” vs “slight improvement” due to physiotherapy, 3) higher pain self-efficacy, and 4) lower pain severity at rest.

In further support of psychosocial factors related to shoulder pain, Coronado et al stated,

In patients with non-specific shoulder pain, associations between pain catastrophizing and fear have been previously reported. Coronado 2018

They cite: George 2009, Lentz 2009, and Menendez 2015.

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Recap

To close, we have evidence that rotator cuff tears appear in asymptomatic populations and increase in prevalence throughout life. Most symptomatic rotator cuff tears tend to follow a natural history of improvement over time. Many clinicians operate from a false premise by dichotomizing traumatic versus degenerative rotator cuff tears to determine an appropriate course of action while choosing surgical repair for those deemed traumatic. Although the necessity of surgical repair is discussed with confidence by many clinicians, there is substantial evidence questioning the validity of surgical intervention and much more uncertainty exists. We have evidence of similar outcomes between surgical intervention and conservative (e.g., exercise therapy) management. Corticosteroid injection therapy appears to provide a small benefit in the short term (less than 8 weeks), but no clear benefit at any time point beyond that. We also have emerging evidence regarding risks of such injections. At this time, exercise therapy appears to be the best course of action based on the totality of evidence. However, given the variability among exercise interventions studied, more well-conducted studies are required to determine the appropriate type and dose of exercise. We should also address psychosocial factors such as self-efficacy and patient expectations to increase the odds of positive long-term outcomes. Overall, the evidence is supportive of conservative management for rotator cuff tears, but whether a particular subset of cases necessitate surgical intervention remains unknown.

We hope this guide has been helpful. If you are struggling with shoulder pain and would like to work with us, please click the ""Get Started" down below.

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References:

1. Wassinger CA, Williams DA, Milosavljevic S, Hegedus EJ. CLINICAL RELIABILITY AND DIAGNOSTIC ACCURACY OF VISUAL SCAPULOHUMERAL MOVEMENT EVALUATION IN DETECTING PATIENTS WITH SHOULDER IMPAIRMENT. Int J Sports Phys Ther. 2015 Aug;10(4):456-63. PMID: 26346446; PMCID: PMC4527193.

2. Plummer HA, Sum JC, Pozzi F, Varghese R, Michener LA. Observational Scapular Dyskinesis: Known-Groups Validity in Patients With and Without Shoulder Pain. J Orthop Sports Phys Ther. 2017 Aug;47(8):530-537. doi: 10.2519/jospt.2017.7268. Epub 2017 Jul 6. PMID: 28683230.

3. Ratcliffe E, Pickering S, McLean S, Lewis J. Is there a relationship between subacromial impingement syndrome and scapular orientation? A systematic review. Br J Sports Med. 2014 Aug;48(16):1251-6. doi: 10.1136/bjsports-2013-092389. Epub 2013 Oct 30. Erratum in: Br J Sports Med. 2014 Aug;48(16):1396. PMID: 24174615.

4. McQuade KJ, Borstad J, de Oliveira AS. Critical and Theoretical Perspective on Scapular Stabilization: What Does It Really Mean, and Are We on the Right Track? Phys Ther. 2016 Aug;96(8):1162-9. doi: 10.2522/ptj.20140230. Epub 2016 Feb 4. PMID: 26847012.

5. Wright AA, Wassinger CA, Frank M, Michener LA, Hegedus EJ. Diagnostic accuracy of scapular physical examination tests for shoulder disorders: a systematic review. Br J Sports Med. 2013 Sep;47(14):886-92. doi: 10.1136/bjsports-2012-091573. Epub 2012 Oct 18. PMID: 23080313.

6. Polaski AM, Phelps AL, Kostek MC, Szucs KA, Kolber BJ. Exercise-induced hypoalgesia: A meta-analysis of exercise dosing for the treatment of chronic pain. PLoS One. 2019 Jan 9;14(1):e0210418. doi: 10.1371/journal.pone.0210418. PMID: 30625201; PMCID: PMC6326521.

7. Testa M, Rossettini G. Enhance placebo, avoid nocebo: How contextual factors affect physiotherapy outcomes. Man Ther. 2016 Aug;24:65-74. doi: 10.1016/j.math.2016.04.006. Epub 2016 Apr 20. PMID: 27133031.

8. Hartman SE. Why do ineffective treatments seem helpful? A brief review. Chiropr Osteopat. 2009 Oct 12;17:10. doi: 10.1186/1746-1340-17-10. PMID: 19822008; PMCID: PMC2770065.

9. Reijneveld EA, Noten S, Michener LA, Cools A, Struyf F. Clinical outcomes of a scapular-focused treatment in patients with subacromial pain syndrome: a systematic review. Br J Sports Med. 2017 Mar;51(5):436-441. doi: 10.1136/bjsports-2015-095460. Epub 2016 Jun 1. PMID: 27251897.

10. Saito H, Harrold ME, Cavalheri V, McKenna L. Scapular focused interventions to improve shoulder pain and function in adults with subacromial pain: A systematic review and meta-analysis. Physiother Theory Pract. 2018 Sep;34(9):653-670. doi: 10.1080/09593985.2018.1423656. Epub 2018 Jan 19. PMID: 29351510.

11. Nodehi Moghadam A, Rahnama L, Noorizadeh Dehkordi S, Abdollahi S. Exercise therapy may affect scapular position and motion in individuals with scapular dyskinesis: a systematic review of clinical trials. J Shoulder Elbow Surg. 2020 Jan;29(1):e29-e36. doi: 10.1016/j.jse.2019.05.037. Epub 2019 Aug 13. PMID: 31420226.

12. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972 Jan;54(1):41-50. PMID: 5054450.

13. Ketola S, Lehtinen J, Rousi T, Nissinen M, Huhtala H, Arnala I. Which patients do not recover from shoulder impingement syndrome, either with operative treatment or with nonoperative treatment? Acta Orthop. 2015;86(6):641-6. doi: 10.3109/17453674.2015.1033309. Epub 2015 Sep 24. PMID: 25809315; PMCID: PMC4750760.

14. Benedetti F, Carlino E, Pollo A. How placebos change the patient's brain. Neuropsychopharmacology. 2011 Jan;36(1):339-54. doi: 10.1038/npp.2010.81. Epub 2010 Jun 30. PMID: 20592717; PMCID: PMC3055515.

15. Beard DJ, Rees JL, Cook JA, et al. Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial The Lancet. 2018; 391(10118):329-338.

16. Paavola M, Malmivaara A, Taimela S, et al. Subacromial decompression versus diagnostic arthroscopy for shoulder impingement: randomised, placebo surgery controlled clinical trial BMJ. 2018.

17. Steuri R, Sattelmayer M, Elsig S, Kolly C, Tal A, Taeymans J, Hilfiker R. Effectiveness of conservative interventions including exercise, manual therapy and medical management in adults with shoulder impingement: a systematic review and meta-analysis of RCTs. Br J Sports Med. 2017 Sep;51(18):1340-1347. doi: 10.1136/bjsports-2016-096515. Epub 2017 Jun 19. PMID: 28630217; PMCID: PMC5574390.

18. Cook T, Lewis J. Rotator Cuff-Related Shoulder Pain: To Inject or Not to Inject? J Orthop Sports Phys Ther. 2019 May;49(5):289-293. doi: 10.2519/jospt.2019.0607. PMID: 31039685.

19. Cuff A, Littlewood C. Subacromial impingement syndrome - What does this mean to and for the patient? A qualitative study. Musculoskelet Sci Pract. 2018 Feb;33:24-28. doi: 10.1016/j.msksp.2017.10.008. Epub 2017 Oct 17. PMID: 29065348.

20. Rossettini G, Carlino E, Testa M. Clinical relevance of contextual factors as triggers of placebo and nocebo effects in musculoskeletal pain. BMC Musculoskelet Disord. 2018 Jan 22;19(1):27. doi: 10.1186/s12891-018-1943-8. PMID: 29357856; PMCID: PMC5778801.

21. Greville-Harris M, Dieppe P. Bad is more powerful than good: the nocebo response in medical consultations. Am J Med. 2015 Feb;128(2):126-9. doi: 10.1016/j.amjmed.2014.08.031. Epub 2014 Sep 16. PMID: 25232716.

22. Karos K, Williams ACdC, Meulders A, Vlaeyen JW. Pain as a threat to the social self: a motivational account Pain. 2018; 159(9):1690-1695.

23. Vlaeyen JWS, Linton SJ. Fear-avoidance and its consequences in chronic musculoskeletal pain: a state of the art. Pain. 2000 Apr;85(3):317-332. doi: 10.1016/S0304-3959(99)00242-0. PMID: 10781906.

24. Park SW, Chen YT, Thompson L, Kjoenoe A, Juul-Kristensen B, Cavalheri V, McKenna L. No relationship between the acromiohumeral distance and pain in adults with subacromial pain syndrome: a systematic review and meta-analysis. Sci Rep. 2020 Nov 26;10(1):20611. doi: 10.1038/s41598-020-76704-z. PMID: 33244115; PMCID: PMC7693267.

25. Tran G, Cowling P, Smith T, Bury J, Lucas A, Barr A, Kingsbury SR, Conaghan PG. What Imaging-Detected Pathologies Are Associated With Shoulder Symptoms and Their Persistence? A Systematic Literature Review. Arthritis Care Res (Hoboken). 2018 Aug;70(8):1169-1184. doi: 10.1002/acr.23554. Epub 2018 Jun 6. PMID: 29513925; PMCID: PMC6099421.

26. Barreto RPG, Braman JP, Ludewig PM, Ribeiro LP, Camargo PR. Bilateral magnetic resonance imaging findings in individuals with unilateral shoulder pain. J Shoulder Elbow Surg. 2019 Sep;28(9):1699-1706. doi: 10.1016/j.jse.2019.04.001. Epub 2019 Jul 3. PMID: 31279721.

27. Herzog R, Elgort DR, Flanders AE, Moley PJ. Variability in diagnostic error rates of 10 MRI centers performing lumbar spine MRI examinations on the same patient within a 3-week period. Spine J. 2017 Apr;17(4):554-561. doi: 10.1016/j.spinee.2016.11.009. Epub 2016 Nov 17. PMID: 27867079.

28. Diercks R, Bron C, Dorrestijn O, Meskers C, Naber R, de Ruiter T, Willems J, Winters J, van der Woude HJ; Dutch Orthopaedic Association. Guideline for diagnosis and treatment of subacromial pain syndrome: a multidisciplinary review by the Dutch Orthopaedic Association. Acta Orthop. 2014 Jun;85(3):314-22. doi: 10.3109/17453674.2014.920991. Epub 2014 May 21. PMID: 24847788; PMCID: PMC4062801.

29. Zadro JR, O'Keeffe M, Ferreira GE, et al. Diagnostic Labels for Rotator Cuff Disease Can Increase People's Perceived Need for Shoulder Surgery: An Online Randomized Controlled Trial J Orthop Sports Phys Ther. 2021; 51(8):401-411.

30. Cohen M, Quintner J, Buchanan D, Nielsen M, Guy L. Stigmatization of Patients with Chronic Pain: The Extinction of Empathy Pain Med. 2011; 12(11):1637-1643.

31. Hanchard NC, Lenza M, Handoll HH, Takwoingi Y. Physical tests for shoulder impingements and local lesions of bursa, tendon or labrum that may accompany impingement . 2013.

32. Chester R, Jerosch-Herold C, Lewis J, Shepstone L. Psychological factors are associated with the outcome of physiotherapy for people with shoulder pain: a multicentre longitudinal cohort study Br J Sports Med. 2018; 52(4):269-275.

33. Martinez-Calderon J, Zamora-Campos C, Navarro-Ledesma S, Luque-Suarez A. The Role of Self-Efficacy on the Prognosis of Chronic Musculoskeletal Pain: A Systematic Review. J Pain. 2018 Jan;19(1):10-34. doi: 10.1016/j.jpain.2017.08.008. Epub 2017 Sep 20. PMID: 28939015.

34. Esteve R, Bendayan R, López-Martínez AE, Ramírez-Maestre C. Resilience and Vulnerability Factors When Pain is Acute as Predictors of Disability: Findings From a Two-Year Longitudinal Study. Pain Med. 2017 Nov 1;18(11):2116-2125. doi: 10.1093/pm/pnx053. PMID: 28505357.

35. Bialosky JE, Bishop MD, Cleland JA. Individual expectation: an overlooked, but pertinent, factor in the treatment of individuals experiencing musculoskeletal pain. Phys Ther. 2010 Sep;90(9):1345-55. doi: 10.2522/ptj.20090306. Epub 2010 Jun 30. PMID: 20592270; PMCID: PMC2931638.

36. Geurts JW, Willems PC, Lockwood C, van Kleef M, Kleijnen J, Dirksen C. Patient expectations for management of chronic non-cancer pain: A systematic review. Health Expect. 2017 Dec;20(6):1201-1217. doi: 10.1111/hex.12527. Epub 2016 Dec 23. PMID: 28009082; PMCID: PMC5689237.

37. Lewis J. The End of an Era? J Orthop Sports Phys Ther. 2018 Mar;48(3):127-129. doi: 10.2519/jospt.2018.0102. PMID: 29490599.

38. Spiegl UJ, Warth RJ, Millett PJ. Symptomatic internal impingement of the shoulder in overhead athletes. Sports Med Arthrosc Rev. 2014 Jun;22(2):120-9. doi: 10.1097/JSA.0000000000000017. PMID: 24787727.

39. Asker M, Brooke HL, Waldén M, Tranaeus U, Johansson F, Skillgate E, Holm LW. Risk factors for, and prevention of, shoulder injuries in overhead sports: a systematic review with best-evidence synthesis. Br J Sports Med. 2018 Oct;52(20):1312-1319. doi: 10.1136/bjsports-2017-098254. Epub 2018 Mar 26. PMID: 29581141.

40. Del Grande F, Aro M, Jalali Farahani S, Cosgarea A, Wilckens J, Carrino JA. High-Resolution 3-T Magnetic Resonance Imaging of the Shoulder in Nonsymptomatic Professional Baseball Pitcher Draft Picks. J Comput Assist Tomogr. 2016 Jan-Feb;40(1):118-25. doi: 10.1097/RCT.0000000000000327. PMID: 26529676.

41. Lee CS, Stetson WB, Goldhaber NH, Davis SM, Brock A, Wosmek J. Magnetic Resonance Imaging Findings in Asymptomatic Elite Volleyball Players Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2017; 33(10):e58-e59.

42. Johansson F, DeBri E, Swärdh L, et al. MRI FINDINGS IN THE SHOULDER OF COMPLETELY ASYMPTOMATIC ADOLESCENT ELITE TENNIS PLAYERS Br J Sports Med. 2014; 48(7):612.2-612.

43. Fredericson M, Ho C, Waite B, Jennings F, Peterson J, Williams C, Mathesonn GO. Magnetic resonance imaging abnormalities in the shoulder and wrist joints of asymptomatic elite athletes. PM R. 2009 Feb;1(2):107-16. doi: 10.1016/j.pmrj.2008.09.004. Epub 2009 Feb 3. PMID: 19627884.

44. Connor PM, Banks DM, Tyson AB, Coumas JS, D'Alessandro DF. Magnetic resonance imaging of the asymptomatic shoulder of overhead athletes: a 5-year follow-up study. Am J Sports Med. 2003 Sep-Oct;31(5):724-7. doi: 10.1177/03635465030310051501. PMID: 12975193.

45. Schär MO, Dellenbach S, Pfirrmann CW, Raniga S, Jost B, Zumstein MA. Many Shoulder MRI Findings in Elite Professional Throwing Athletes Resolve After Retirement: A Clinical and Radiographic Study. Clin Orthop Relat Res. 2018 Mar;476(3):620-631. doi: 10.1007/s11999.0000000000000042. PMID: 29408833; PMCID: PMC6260028.

46. Bell DR, Post EG, Biese K, Bay C, Valovich McLeod T. Sport Specialization and Risk of Overuse Injuries: A Systematic Review With Meta-analysis . 2018; 142(3).

47. Jones CM, Griffiths PC, Mellalieu SD. Training Load and Fatigue Marker Associations with Injury and Illness: A Systematic Review of Longitudinal Studies. Sports Med. 2017 May;47(5):943-974. doi: 10.1007/s40279-016-0619-5. PMID: 27677917; PMCID: PMC5394138.

48. Eckard TG, Padua DA, Hearn DW, Pexa BS, Frank BS. The Relationship Between Training Load and Injury in Athletes: A Systematic Review. Sports Med. 2018 Aug;48(8):1929-1961. doi: 10.1007/s40279-018-0951-z. Erratum in: Sports Med. 2020 Jun;50(6):1223. PMID: 29943231.

49. Lauersen JB, Andersen TE, Andersen LB. Strength training as superior, dose-dependent and safe prevention of acute and overuse sports injuries: a systematic review, qualitative analysis and meta-analysis Br J Sports Med. 2018; 52(24):1557-1563.

50. Ivarsson A, Johnson U, Andersen MB, Tranaeus U, Stenling A, Lindwall M. Psychosocial Factors and Sport Injuries: Meta-analyses for Prediction and Prevention Sports Med. 2016; 47(2):353-365.

51. Littlewood C, Rangan A, Beard DJ, Wade J, Cookson T, Foster NE. The enigma of rotator cuff tears and the case for uncertainty Br J Sports Med. 2018; 52(19):1222-1222.

52. Malliaras P, Rathi S, Burstein F, Watt L, Ridgway J, King C, Warren N. 'Physio's not going to repair a torn tendon': patient decision-making related to surgery for rotator cuff related shoulder pain. Disabil Rehabil. 2021 Feb 12:1-8. doi: 10.1080/09638288.2021.1879945. Epub ahead of print. PMID: 33577359.

53. Ryösä A, Laimi K, Äärimaa V, Lehtimäki K, Kukkonen J, Saltychev M. Surgery or conservative treatment for rotator cuff tear: a meta-analysis. Disabil Rehabil. 2017 Jul;39(14):1357-1363. doi: 10.1080/09638288.2016.1198431. Epub 2016 Jul 6. PMID: 27385156.

54. Longo UG, Risi Ambrogioni L, Candela V, et al. Conservative versus surgical management for patients with rotator cuff tears: a systematic review and META-analysis BMC Musculoskelet Disord. 2021; 22(1).

55. Fahy K, Galvin R, Lewis J, Mc Creesh K. Exercise as effective as surgery in improving quality of life, disability, and pain for large to massive rotator cuff tears: A systematic review & meta-analysis Musculoskeletal Science and Practice. 2022; 61:102597-.

56. Khatri C, Ahmed I, Parsons H, et al. The Natural History of Full-Thickness Rotator Cuff Tears in Randomized Controlled Trials: A Systematic Review and Meta-analysis Am J Sports Med. 2018; 47(7):1734-1743.

57. Kwong CA, Ono Y, Carroll MJ, Fruson LW, More KD, Thornton GM, Lo IKY. Full-Thickness Rotator Cuff Tears: What Is the Rate of Tear Progression? A Systematic Review. Arthroscopy. 2019 Jan;35(1):228-234. doi: 10.1016/j.arthro.2018.07.031. Epub 2018 Nov 22. PMID: 30472019.

58. Boorman RS, More KD, Hollinshead RM, Wiley JP, Brett K, Mohtadi NG, Nelson AA, Lo IK, Bryant D. The rotator cuff quality-of-life index predicts the outcome of nonoperative treatment of patients with a chronic rotator cuff tear. J Bone Joint Surg Am. 2014 Nov 19;96(22):1883-8. doi: 10.2106/JBJS.M.01457. PMID: 25410506.

59. Boorman RS, More KD, Hollinshead RM, Wiley JP, Mohtadi NG, Lo IKY, Brett KR. What happens to patients when we do not repair their cuff tears? Five-year rotator cuff quality-of-life index outcomes following nonoperative treatment of patients with full-thickness rotator cuff tears. J Shoulder Elbow Surg. 2018 Mar;27(3):444-448. doi: 10.1016/j.jse.2017.10.009. PMID: 29433644.

60. Cook T, Minns Lowe C, Maybury M, Lewis JS. Are corticosteroid injections more beneficial than anaesthetic injections alone in the management of rotator cuff-related shoulder pain? A systematic review Br J Sports Med. 2018; 52(8):497-504.

61. Desai VS, Camp CL, Boddapati V, Dines JS, Brockmeier SF, Werner BC. Increasing Numbers of Shoulder Corticosteroid Injections Within a Year Preoperatively May Be Associated With a Higher Rate of Subsequent Revision Rotator Cuff Surgery Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2019; 35(1):45-50.

62. Agarwalla A, Puzzitiello RN, Mascarenhas R, Sumner S, Romeo AA, Forsythe B. Preoperative Injections May Be an Iatrogenic Cause of Reoperation After Arthroscopic Rotator Cuff Repair Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2019; 35(2):325-331.

63. Jeanfavre M, Husted S, Leff G. EXERCISE THERAPY IN THE NON-OPERATIVE TREATMENT OF FULL-THICKNESS ROTATOR CUFF TEARS: A SYSTEMATIC REVIEW. Int J Sports Phys Ther. 2018 Jun;13(3):335-378. PMID: 30038823; PMCID: PMC6044593.

64. Coronado RA, Seitz AL, Pelote E, Archer KR, Jain NB. Are Psychosocial Factors Associated With Patient-reported Outcome Measures in Patients With Rotator Cuff Tears? A Systematic Review. Clin Orthop Relat Res. 2018 Apr;476(4):810-829. doi: 10.1007/s11999.0000000000000087. PMID: 29481342; PMCID: PMC6260082.

65. George SZ, Hirsh AT. Psychologic influence on experimental pain sensitivity and clinical pain intensity for patients with shoulder pain. J Pain. 2009 Mar;10(3):293-9. doi: 10.1016/j.jpain.2008.09.004. Epub 2008 Dec 13. PMID: 19070551; PMCID: PMC2672100.

66. Lentz TA, Barabas JA, Day T, Bishop MD, George SZ. The relationship of pain intensity, physical impairment, and pain-related fear to function in patients with shoulder pathology. J Orthop Sports Phys Ther. 2009 Apr;39(4):270-7. doi: 10.2519/jospt.2009.2879. PMID: 19346624.

67. Menendez ME, Baker DK, Oladeji LO, Fryberger CT, McGwin G, Ponce BA. Psychological Distress Is Associated with Greater Perceived Disability and Pain in Patients Presenting to a Shoulder Clinic. J Bone Joint Surg Am. 2015 Dec 16;97(24):1999-2003. doi: 10.2106/JBJS.O.00387. PMID: 26677233.